I have next code:
PhotoFactory factory = PhotoFactory.getFactory (PhotoResource.PICASA);
PhotoSession session = factory.openSession (login, password);
PhotoAlbum album = factory.createAlbum ();
Photo photo = factory.createPhoto ();
album.addPhoto (photo);
if (session.canUpload ()) {
session.uploadAlbum (album);
}
session.close ();
I'm not sure that I've chosen correct name. It's not so important but I'm just curious what had you chosen in my case. Another version is manager:
PhotoManager manager = PhotoManager.getManager (PhotoResource.PICASA);
PhotoSession session = manager.openSession (login, password);
PhotoAlbum album = manager.createAlbum ();
Photo photo = manager.createPhoto ();
album.addPhoto (photo);
if (session.canUpload ()) {
session.uploadAlbum (album);
}
session.close ();
UPD: I've just found next example at hibernate javadocs:
Session sess = factory.openSession();
Transaction tx;
try {
tx = sess.beginTransaction();
//do some work
...
tx.commit();
}
Is that a naming mistake?
At a very high level, I'd call it a Factory if it's only responsible for creating instances of classes; and a Manager if it needs to oversee the ongoing existence of objects, and how they relate to other objects, etc.
In the code snippets you've posted you're only creating objects and thus, in my opinion, Factory is an appropriate name. Though you should bear in mind what the conceptual responsibilities of the class are and whether they might expand in future.
That said, I would classically expect a factory to not have to worry about creating sessions itself but rather have sessions passed into their createFoo calls as required, so there's definitely some fudge factor as things are set up. I think personally I would have some other abstract entity responsible for creating sessions, and then pass these into the PhotoFactory.
I would choose the second solution (manager), since objects ending with 'Factory' are generally considered implementations of the factory pattern, which essentially creates new instances of objects. This is not the case in your example, since it manages a session for a particular service.
What's nice in this example, is that in fact your first static method call getManager is in fact a factory, since it creates instances of Manager objects.
Related
In Service Fabric I am trying to call an ActorService and get a list of all actors. I'm not getting any errors, but no actors are returned. It's always zero.
This is how I add actors :
ActorProxy.Create<IUserActor>(
new ActorId(uniqueName),
"fabric:/ECommerce/UserActorService");
And this is how I try to get a list of all actors:
var proxy = ActorServiceProxy.Create(new Uri("fabric:/ECommerce/UserActorService"), 0);
ContinuationToken continuationToken = null;
CancellationToken cancellationToken = new CancellationTokenSource().Token;
List<ActorInformation> activeActors = new List<ActorInformation>();
do
{
var proxy = GetUserActorServiceProxy();
PagedResult<ActorInformation> page = await proxy.GetActorsAsync(continuationToken, cancellationToken);
activeActors.AddRange(page.Items.Where(x => x.IsActive));
continuationToken = page.ContinuationToken;
}
while (continuationToken != null);
But no matter how many users I've added, the page object will always have zero items. What am I missing?
The second argument int in ActorServiceProxy.Create(Uri, int, string) is the partition key (you can find out more about actor partitioning here).
The issue here is that your code checks only one partition (partitionKey = 0).
So the solutions is quite simple - you have to iterate over all partitions of you service. Here is an answer with code sample to get partitions and iterate over them.
UPDATE 2019.07.01
I didn't spot this from the first time but the reason why you aren't getting any actors returned is because you aren't creating any actors - you are creating proxies!
The reason for such confusion is that Service Fabric actors are virtual i.e. from the user point of view actor always exists but in real life Service Fabric manages actor object lifetime automatically persisting and restoring it's state as needed.
Here is a quote from the documentation:
An actor is automatically activated (causing an actor object to be constructed) the first time a message is sent to its actor ID. After some period of time, the actor object is garbage collected. In the future, using the actor ID again, causes a new actor object to be constructed. An actor's state outlives the object's lifetime when stored in the state manager.
In you example you've never send any messages to actors!
Here is a code example I wrote in Program.cs of newly created Actor project:
// Please don't forget to replace "fabric:/Application16/Actor1ActorService" with your actor service name.
ActorRuntime.RegisterActorAsync<Actor1> (
(context, actorType) =>
new ActorService(context, actorType)).GetAwaiter().GetResult();
var actor = ActorProxy.Create<IActor1>(
ActorId.CreateRandom(),
new Uri("fabric:/Application16/Actor1ActorService"));
_ = actor.GetCountAsync(default).GetAwaiter().GetResult();
ContinuationToken continuationToken = null;
var activeActors = new List<ActorInformation>();
var serviceName = new Uri("fabric:/Application16/Actor1ActorService");
using (var client = new FabricClient())
{
var partitions = client.QueryManager.GetPartitionListAsync(serviceName).GetAwaiter().GetResult();;
foreach (var partition in partitions)
{
var pi = (Int64RangePartitionInformation) partition.PartitionInformation;
var proxy = ActorServiceProxy.Create(new Uri("fabric:/Application16/Actor1ActorService"), pi.LowKey);
var page = proxy.GetActorsAsync(continuationToken, default).GetAwaiter().GetResult();
activeActors.AddRange(page.Items);
continuationToken = page.ContinuationToken;
}
}
Thread.Sleep(Timeout.Infinite);
Pay special attention to the line:
_ = actor.GetCountAsync(default).GetAwaiter().GetResult();
Here is where the first message to actor is sent.
Hope this helps.
I'm trying to use a background task to gather Likes/Comments from the Facebook Graph APi and use that to drive our blog's trending.
Here the trendingModels have already been populated and are being used to fill in the TrendingParts.GraphId and TrendingParts.TrendingValue.
I'm not getting any exceptions and the properties on TrendingPart point to the fields in the TrendingPartRecord.
Yet nothing persists to the database, any ideas why?
_orchardsServices is IOrchardServices
var articleParts = _orchardService.ContentManager.GetMany<TrendingPart>(
trendingModels.Select(r => r.OrchardId).ToList(),
VersionOptions.Published,
QueryHints.Empty);
// Cycle through the records and update them from the matching model
foreach (var articlePart in articleParts)
{
ArticleTrendingModel trendingModel = trendingModels.Where(r => r.OrchardId == articlePart.Id).FirstOrDefault();
if(trendingModel != null)
{
// Not persisting to the database, WHY?
// What's missing?
// If I'm understanding things properly nHibernate should push this to the db autoMagically.
articlePart.GraphId = trendingModel.GraphId;
articlePart.TrendingValue = trendingModel.TrendingValue;
}
}
Edit:
It's probably worth noting that I can update and publish the fields on the TrendingPart in the admin panel but the saved changes don't appear in the MyModule_TrendingPartRecord table.
The solution was to change my Service to a transient dependency using ITransientDependency.
The service was holding a reference to the PartRecords array and because it was treated as a Singleton it never disposed and the push to the database was never made.
I would like to use the item that has been just been saved in the completion block of Magical Record saveWithBlock method. For example:
//Get the ID of an existing NSManagedObject to use in the save block (if it exists)
NSManagedObjectID *objectRef = [self.object objectID];
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext){
//This method either loads an existing object and makes changes or creates a new entity in localContext
NSManagedObject *itemToSave = [self prepareItemInContext:localContext WithID: objectRef];
} completion:^(BOOL success, NSError *error) {
if (success) {
//here I want to get at the object 'itemToSave' that was either created in the save block (with a new objectID) or updated (with the ID objectRef)
Well, you need to have a reference to your external context to load the object with that ID:
NSManagedObjectContext *outsideContext = //...
NSManagedObjectID *objectID = //...
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
} completion:^(BOOL success, NSError *error) {
NSManagedObject *newlySavedObject = [outsideContext existingObjectWithID:objectID];
//...do stuff here
}];
Generally, however, I would discourage this usage. I would instead recommend keeping any predicates or means of reloading your data set handy, and dump and refetch fresh data from the store. This will give you proper object references. Another, more precise way of updating objects in other contexts is to listen to the NSManagedObjectContextDidSaveNotification and merge this updates into your context. From there, your data will be "refreshed" and as long as you're KVO'ing a property, or using a NSFetchedResultsController with a delegate, your updates will propagate to the UI (or other destination).
Either just use self.object or, if you create a new object and insert it (presumably because objectRef is nil) then you should get the corresponding new object from the main thread context and use that.
How you do that shuffle is the interesting part. It isn't exactly clear why you're using a background context at the moment so you can also consider changing that, which removes all of the complexity.
If you need to keep the background context then you need to decide on how to get that data back to the main thread. Generally, you could use performBlockAndWait: inside your current block to get the new object from the main context and then store it into a property on your class so you can use it in the completion block. This would be setting the self.object property.
I need to write a service that connects to CRM, and returns with a list of all of the entity available on the server (custom or otherwise).
How can I do this? To be clear, I am not looking to return all data for all entities. Just a list of every type, regardless of whether any actually exist.
You need to use RetrieveAllEntitiesRequest
RetrieveAllEntitiesRequest request = new RetrieveAllEntitiesRequest()
{
EntityFilters = EntityFilters.Entity,
RetrieveAsIfPublished = true
};
// service is the IOrganizationService
RetrieveAllEntitiesResponse response = (RetrieveAllEntitiesResponse)service.Execute(request);
foreach (EntityMetadata currentEntity in response.EntityMetadata)
{
string logicalName = currentEntity.LogicalName;
// your logic here
}
note that you will get also system or hidden entities, like wizardpage or recordcountsnapshot
You will probably find these sections of the MSDN useful:
Customize Entity Metadata (lookout for the samples linked on that page).
Retrieve and Detect Changes to Metadata.
Here's another one for releasing objects created by reflection:
We're working with a reporting tool (Active Reports 6) which creates a dll for each report.
We have lots of clients that use similar but still unique reports.
Reports are read through a web interface.
We run multiple sites, one for each client.
Our choices are:
1) Put all the reports in one big project which will be called by all the sites.
Cost: It will need to be recompiled every time we make a small change to any one report, potentially creating problems for all sites.
2) Create a whole bunch of similar little projects, with one for each site - let's say for sake of space that this creates problems, too.
3) Create a "Report Factory" which will use reflection to wire-up report dlls as needed.
We chose "3".
Problem: The final product works fine except for one thing: It won't release the report dll when done.
There is not currently a problem with the operation within a test environment, but if you try to do anything in the folder with the report dlls, you get the following error message: "This action can't be completed because the folder or a file in it is open in another program"
After research on this site and others, we realized that we needed an AppDomain for each call which can be cleanly unloaded.
After still having problems, we realized that the AppDomainSetup object needed to have a setting that allowed it to optimize for multiple users (LoaderOptimization.MultiDomain)
That didn't work.
Unfortunately, the base object (Active 6 report) can not be serialized, so we can't make a deep copy and chuck the original object.
After doing all of this, we're still experiencing problems.
Here is the code (C#):
private object WireUpReport(ReportArgs args)
{
//The parameter 'args' is a custom type (ReportArgs) which merely contains a
name/value pair collection.
object myReport = null;
string sPath = String.Empty;
string sFriendlyName = String.Empty;
sFriendlyName = System.Guid.NewGuid().ToString();
Assembly asmReport = null;
AppDomainSetup ads = null;
AppDomain adWireUp = null;
ConstructorInfo ci = null;
Type myReportType = null;
Type[] parametypes = null;
object[] paramarray = null;
object retObject = null;
try
{
//Get Report Object
sPath = GetWireUpPath(args); //Gets the path to the required dll; kept in a config file
//This parameter is used in an overloaded constructor further down
ads = new AppDomainSetup();
ads.ApplicationBase = Path.GetDirectoryName(sPath);
ads.LoaderOptimization = LoaderOptimization.MultiDomain;
adWireUp = AppDomain.CreateDomain(sFriendlyName, AppDomain.CurrentDomain.Evidence, ads);
asmReport = adWireUp.GetAssemblies()[0];
asmReport = Assembly.LoadFrom(sPath);
//Create parameters for wireup
myReportType = asmReport.GetExportedTypes()[0];
parametypes = new Type[1];
parametypes[0] = typeof(ReportArgs);
ci = myReportType.GetConstructor(parametypes);
paramarray = new object[1];
paramarray[0] = args;
//Instantiate object
myReport = ci.Invoke(paramarray);
return myReport;
}
catch (Exception ex)
{
throw ex;
}
finally
{
//Make sure Assembly object is released.
if (adWireUp != null)
{
AppDomain.Unload(adWireUp);
}
if (asmReport != null)
{
asmReport = null;
}
if (ads != null)
{
ads = null;
}
if (adWireUp != null)
{
adWireUp = null;
}
if (ci != null)
{
ci = null;
}
if (myReportType != null)
{
myReportType = null;
}
if (parametypes != null)
{
parametypes = null;
}
if (paramarray != null)
{
paramarray = null;
}
}
}
The object which is returned from this code is cast as type ActiveReports and then passed around our application.
Any help would be deeply appreciated. Thanks
Your code looks like you are seriously misunderstanding how to interact with a separate AppDomain.
Think of communicating with an AppDomain like talking to someone who's currently in another country. You know where they are, but you can't just walk over and talk to them. If you want them to do something for you, you have to open up a line of communication and tell them what you need.
The way that you open that line of communication is by defining a proxy object that can be created inside the other AppDomain and then cross the boundary back to your current AppDomain. Being able to cross the boundary requires that your object either be marked as [Serializable] or inherit from MarshalByRefObject. Because we actually want to talk to a reference in the other AppDomain and not just have a copy of it, we need the proxy to do the latter.
private class CrossDomainQuery : MarshalByRefObject
{
public void LoadDataFromAssembly(string assemblyPath)
{
var assembly = Assembly.LoadFrom(assemblyPath);
//TODO: Do something with your assembly
}
}
There is a method on the AppDomain called CreateInstanceAndUnwrap() that will create an instance of that communication object inside the other AppDomain and then hand you back a __TransparentProxy object that can be cast to the proxy type.
var crossDomainQuery = (CrossDomainQuery)adWireUp.CreateInstanceAndUnwrap(
typeof(CrossDomainQuery).Assembly.FullName,
typeof(CrossDomainQuery).FullName);
Once you have that proxy object, you can call methods on it and they will be invoked in the other AppDomain.
crossDomainQuery.LoadDataFromAssembly(assemblyPath);
So how is this different from what your current example code is doing?
Your current code does not actually execute anything useful inside the other AppDomain.
adWireUp = AppDomain.CreateDomain(sFriendlyName, AppDomain.CurrentDomain.Evidence, ads);
asmReport = adWireUp.GetAssemblies()[0];
asmReport = Assembly.LoadFrom(sPath);
This creates a new AppDomain, but then it loads all of the assemblies from that AppDomain into your current AppDomain. Additionally, it explicitly loads your report assembly into your current AppDomain.
Creating an AppDomain and calling methods on it doesn't mean that your code is executing inside of it any more than reading about another country means that you're now talking to someone inside it.
Even if you do create a proxy object and execute code inside that other AppDomain, there are a few things to be aware of.
1) Both AppDomains must be able to see the type used for the proxy, and you may have to handle AssemblyResolve events for either AppDomain manually (at least temporarily) to help resolve that.
2) AppDomains are fairly expensive to create. Generally, they are not used in situations where you need to spin something up really quickly, take some action and disappear. You should plan on either keeping them around as long as you can or be prepared to take the performance hit on every call.
3) You've said that the report type that you're instantiating is not serializable, and being able to serialize the object is a requirement for passing that type back from the other AppDomain. Defining a serializable class that can transport relevant data across the boundary and using that to pass the report data might be an option, but you'll have to determine if that works for your particular situation.
Also, as an aside, unless you have logic that depends on variables being set to null, setting everything to null in your finally does nothing useful and complicates your code.